The post office will do a one-way insurance surprisingly cheaply. Its very difficult to find through the usual insurers!
They will cover you just for the journey + a few extra days if you want to cover any delay or stop-over. Its a good to have as anyone can need emergency medical aid or have damaged luggage. I think it is only available by phone, not "over the counter". I googled the number.
Good luck for your future life in NZ!

We used the post office travel insurance and did it online. Never needed to use it so don't know how good they would be in a crisis but at least we had peace of mind. It also covered our luggage which we felt was important as we did bring a lot with us to keep us going.